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Re: Tofu 'may raise risk of dementia'

Re: Tofu 'may raise risk of dementia'

This is why I stick to no more than 2 servings of soy per day (usually a lot less). Sure it's convenient when you are new to veganism but I prefer to stick to trusted foods like rice, beans, fruit, breads, and veggies.

Re: Tofu 'may raise risk of dementia'

Must say this study sounds a bit suspect to me, based on the limited information in the report. If the people had memory problems, how did the researchers find out how much tofu they'd eaten? And they used a modest-sized sample from one region - did they control for variables that might be associated with tofu eating, like being poor (in oriental countries I believe people often eat meat rather than tofu if they can afford to)? Also we'll probably find it was funded by the tempeh marketing board or summat.

Regardless, it doesn't seem sensible to eat any one food all the time - a variety of foods seems a better insurance policy.

Memory: Tempeh and tofu, for better or worse

According to the Indonesian article above, published in february this year, tempeh is good for your memory, while tofu (eaten twice or more per day) is bad for you - if you're above 68 years old. The study is now being discussed in several European newspapers. According to the article linked above, people (especially women) over 68 who consumed tofu (a processed or semi-processed soy product) more than twice a day had a worse memory than those who rarely eat it. If they also ate tempeh - another soy product, the risk of dementia was reduced.

The study was performed on 712 respondents from West Java and Yogyakarta, with ages ranging from 52 to 98 years.

An excerpt:

Professor Hogervorst said basic soy products, including Indonesian traditional foods of tofu and tempeh, had positive effects on memory because of their phytoestrogen content, which have estrogenic effects, and that a trial using soy extract showed women administered with the extract right after entering menopause recorded improvements in cognitive activities, including memory and concentration.

Similar affects were recorded with estrogen treatments in recently menopausal women with Alzheimer's disease.
However, she said, if the hormone treatment was applied on women more than 65 years of age, dementia was increased.
"This is a new finding that tempeh can offset tofu's negative effects to memory," Hogervorst said.
"It's perhaps because of tempeh's level of genistein, which is twice higher than that of tofu, or because it contains a high level of folate."

Hogervorst said tofu's associations with a worsening memory might be attributed to formaldehyde contents in the soy product.
"The culprit may be formaldehyde but we need further study to confirm this."

If the culprit is formaldehyde, the studies can't be translated to European conditions - because formaldehyde is banned here due to it's cancer promoting effect.

When these studies about the positive/negative effects of two different soy based products have on memory, are referred to in some Western newspapers, only the negative effect is mentioned.

BBC refers to the study on the Indonesians, and writes that tofu (which as we know is used by some veg*ns, and not by others)'may raise risk of dementia'.

Unlike the Indonesian article, BBC doesn't specifically mention that these people ate tofu twice a day - BBC writes at least once a day. Whoever is right, I haven't met anyone who eats tofu every day. Tofu is mainly made by soy and water plus a coagulant, and it's quite likely that people with a weak economy and little knowledge about nutrition (in certain countries, where tofu has been commonly used for hundreds of years) may eat too much of it. Eating too much of anything isn't good. BBCs title is about the bad effect of too much tofu, not about the good effect of tempeh.

In case you are interested, here's the original article: http://content.karger.com/ProdukteDB...84&hl=1&q=Tofu The abstract of the article starts with "Cell culture studies suggest that phytoestrogens, abundant in soy products such as tempe and Tofu, could protect against cognitive decline." Tempeh is mentioned three times in the abstract alone.

Now, last up: the 'news' reaches Norway and a tabloid newspaper called Verdens Gang (VG) and a journalist called Mona Grivi Norman. They have looked at the Daily Mail article, ignore the specific info about eating tofu daily or twice a day, they don't mention tempeh at all, they don't even restrict themselves to say that this is about certain elements in certain soy products if eaten daily/twice a day in Indionesia, their title simply says "Vegetarmat øker Alzheimer-risiko" ("Vegetarian food increases Alzheimer risk").

We know that a lot of people only read headers, and not full articles. The actual article in VG contains a statement from a local researcher who rejects that vegetarians are more likely to get Alzheimer than others, due to all the antioxidants we consume, still: the header says that vegetarian food increases Alzheimer risk. The subtitle says that 'soy products causes memory loss among elderly' - not mentioning that the study is about two soy products, one with a good and one with a bad effect on memory, nor mentioning that lots of vegetarians and vegans hardly use any soy products at all, or that soy is commonly used by non-vegetarians (soy oil, soy margarine, soy sauce etc).

Why did these Indonesian women from Java between 52 and 98 have low memory, and why did they eat all this tofu? How was it processed? Did they believe that tofu is a superfood, and that it would help them improve their health/memory (not unlikely since some of them were close to 100 years, and memory loss and poor health is common among elderly). Did they eat so much tofu because they couldn't afford / have access to enough fresh, unprocessed food? Were they actually vegetarians? Tofu is widely available in Malaysia, Singapore, Thailand and Indonesia, and isn't something that's only eaten by vegetarians. Not that it really matters; if vegetarians often eat more tofu than others, and too much tofu is bad for people (eg. over a certain age), a warning is absolutely useful and welcome, but knowing how many vegetarians and vegans that exist out there, and knowing how few people that make their own tofu, and knowing the small amounts of tofu that are sold in lots of health food stores, I doubt that any vegans eat tofu daily. I could of course be wrong.

Re: Memory: Tempeh and tofu, for better or worse

Yes, as usual the popular press's reporting of a scientific study is superficial and misleading.

I don't think you can tell from the abstract how often the frequent tofu eaters ate tofu as they just seem to have tested to see if there was a correlation between tofu-eating and memory loss (am too mean to fork out $25 for the full article - perhaps someone will be able to get it from their university's on-line library, mine doesn't subscribe to that particular journal unfortunately).

If they really ate tofu once or twice a day, I suspect this may be more characteristic of Indonesians than of vegans!

Re: High levels of tofu 'may raise risk of dementia'?

It does sound a little suspect. My guess is we'll find out it was funded by the meat and dairy industries.

I also suspect that if you're eating highly processed foods (many of which have soy in them in the weiredest places you wouldn't suspect, it's in almost every highly processed food - and in the US that means GMO soy) - that's not going to be good for you, whether or not it's the highly processed soy in those products.

I have trouble believing that if you're eating plain old fresh tofu, it's worse for you than all the known problems with eating a meat and dairy diet.

Re: Memory: Tempeh and tofu, for better or worse

am too mean to fork out $25 for the full article

I did have a look at the original article.

A few interesting points:

As expected, the word vegetarian (or vegan) wasn't mentioned at all.
Unlike what the article in VG and Daily Mail claims, the study didn't warn against tofu and 'similar products', on the contrary, it suggests that the only similar product mentioned, tempeh ("tempeh is an adaptation of tofu to the tropical climates of Indonesia") - has a positive effect on memory.
Most participants consumed soy products on a daily basis.
65% of the group consumed both soy products (tofu and tempeh) once or more than once daily.
Tofu had "a small negative association with memory" but memory performance was positively linked with other food intake.
Tempeh was "independently significantly related to better IR memory performance (learning ability, "immediate recall") - with a similar trend for DR ("delayed recall").
Alzheimer wasn't mentioned in the article at all.
Fruit was also found to have a positive association with both IR and DR.
Their diet wasn't monitored by the researchers, but was reported by each person (or his/her carer):

Another limitation is related to self-report of food consumption, which may not be a reliable measure of actual phytoestrogen intake. In previous studies the Food Frequency Questionnaire (on which these questions were based) was shown to give a valid reflection of isoflavone levels, which were also relatively reliable over time However, cases with memory deficiency and dementia are known to underreport the intake of foods and medication due to the very nature of their morbidity. Carers, when present (in 40% of both the suspected cases and controls), substantiated the self-report data.

In other words: the food data may be wrong in among some of the most dement participants, simply because they may not remember what food and medication they have been taking.

The researchers used a word memory test, and a mention a limitation in the study:

Possibly different test procedures [e.g. translations to Sundanese not sufficiently comparable to Bahasa Indonesia (for Jakarta) and Javanese (for Borobudur)] or additional variance caused by different testers between the sites could be responsible for the lack of significant associations of soy products with memory for Sumedang. However, post hoc analyses did show that positive associations between memory performance and the intake of fruit in the Sundanese were maintained, independently of age, education, sex and the intake of other foods. This could indicate that potential methodological differences were insufficient to confound the results between the sites.

Another mentioned limitation:

There are several methodological limitations to the present study. Firstly, the sampling methods do not allow us to generalize the results.

Some of the women were younger than 60 and may still have had intact menstrual function which could have interacted with the effect of phytoestrogens on the brain (which is a possible reason for the small negative association with tofu).

In short: - the food/medication data the study was based upon may be wrong. The researchers don't mention vegetarians or Alzheimer, and state that generalizations cannot be made based on the existing data. Most of the participants ate both tofu and tempeh at least daily - we're talking about a very high intake of soy products.

A couple of interesting things: The study doesn't claim that soy as such has a bad effect on elderly people, but that tofu has a 'small negative association'. As a possible explanation, they mention that...

According to the Departments of Public Health at the Universities of Jakarta and Yogyakarta formaldehyde is often added to tofu (but not tempe) to preserve its freshness. Formaldehyde can induce oxidative damage to the frontal cortex and hippocampal tissue...

Maybe it was the formaldehyde (existing in tofu, but not in tempeh) that caused the memory problems among elderly.

The positive effect of tempeh - which has significant antioxidantive but also anti-inflammatory and antihrombotic effects - all which are potentially important for prevention of dementia and cognitive decline.

The study mentions that "other compounds than folate in tempe could thus be responsible for the protective association identified between tempe consumption and memory performance."

The question of B12 production in tempeh fermentation is an important and confusing issue, as this vitamin is extremely important for vegetarians and vegans. The most thorough studies show that while most Indonesian tempeh does contain B12, European and American mass-produced tempeh does not. It is now thought that this is because Indonesian tempeh is made not only with the mold Rhizopus oligosporus, but also with various "contaminating" bacteria such as Klebsiella pneumoniae and Citrobacter freundii.

This isn't quite correct - read more about B12 levels in Canadian lab produced tempeh here: Why does (some) tempeh contain B12?... still, even if Candian tempeh has been found to contain even more b12 than Inonesian tempeh (the poor B12 molecules probably don't know or care which country they are in anyway ), Indonesian tempeh has been mention many times as a potential useful B12 soruce.

Anyway - Indonesian tempeh may contain B12 usable for humans, and the formaldehyde used in tofu may have a negative effect on B12, according to the following and other sources:

The 8-page report concludes that "in the present study higher intake of tofu was found to be related to lower memory performance, while tempe may offset this. Future studies should validate this finding and investigate possible mechanisms of action." It will be interesting to see if they can find any links between B12 in tempeh and dementia/memory functions, because this could be a very valid contribution to the discussion about the bioavailability (for humans) of tempeh made with certain bacteria cultures.

Meanwhile, I won't worry too much about journalists manufacturing unfounded generalizations based on studies from researchers who say that the sampling methods "do not allow us to generalize the results" - or on studies with so many variables including possible translation problems, people with an extremely high intake of processed soy products (possible processed with a banned (in Europe) carcinogen cancer-causing substance, namely formaldehyde, and partially based on data from participants who possible don't remember what they ate, which medication they possibly took.

The report also mentions that intake of rice, fruit (whole or as juice), orange or red vegetables, green vegetables and fish all has previously been found to lower the dementia risk.

Since googling may attract some occasional visitors to this thread, let me also mention that an old study, reported on PubMed about the incidence of dementia and intake of animal products found that "The matched subjects who ate meat (including poultry and fish) were more than twice as likely to become demented as their vegetarian counterparts (relative risk 2.18, p = 0.065) and the discrepancy was further widened (relative risk 2.99, p = 0.048) when past meat consumption was taken into account" - probably due to veg*ns' higher intake of antioxidants and folate.

Re: Memory: Tempeh and tofu, for better or worse

A few additional notes based on the info from the actual research paper...

• In spite of what some journalists claim, they did NOT study other soy products than tofu and tempeh: "Too few
people (6%) consumed soy milk or other soy products, so these data were not included in the analyses."

• There were significant differences both in memory performance results between the different locations sites, with participants in Jakarta scoring significantly higher than those in the rural areas of Sumedang and Borobudur. This could be explained the fact that the participants were overall younger and better educated in Jakarta but it was also mentioned that those in the two other rural locations (surprisingly) consumed less fruit and vegetables than those in Jakarta. (Since veg*ns normally eat more fruit/vegetables than non-vegans, this could possibly shred some light on why dementia was twice as common among meat eaters than in veg*ns in the study mentioned in my previous post).

Intake of fruit and vegetables was positively associated with improved memory improvement. Some of the participants didn't eat fruit or vegetables at all: "All participants ate rice at least daily, but fruit, vegetables and fish were not consumed by everyone".

Looking at the table in the research paper, 6 times as many participants from Jakarta (who were scoring significantly higher than those in the rural areas) consumed orange/red vegetables, and circa 7 times as many participants from Jakarta consumed fruit/juice as those in rural Borobudur, but the of tofu/tempeh consumption showed up with similar numbers. Since not all the participants were eating fruit/vegetables, it's even possible the results from those with the very high intake of tofu isn't a result of eating all this tofu, but a result of eating way too little - or no - fruit/vegetables (both known for having a good effect on memory).

(On another note, do we really know if people with higher education have better memory performance because of their education/because they are 'used to' using their brain/memory more than others - or is it the other way round: did they succeed at getting an higher education because they had better memory to start with? Likewise, do we always know that fruit/vegetables cause improved brain functionality - or do we see that people with better functioning brain simply are smart enough to eat more plants?)

• The researches don't claim that soy or soy products is the cause of the negative memory performance among those with a very high tofu consumption, but firmly states that "It is unclear whether these negative associations could be attributed to potential toxins or to its phytoestrogen levels." Phytoestrogen occurs naturally in these products, Formaldehyde doesn't.

Another study, the so called Honolulu Asia Aging Study - on Asian immigrants, which shoed that "men and women who consume high levels of tofu in midlife and later life had worse cognitive function". I haven't looked at it, but I have no reason to assume that it's wrong (or to defend high use of processed soy products/tofu) at all. Nevertheless, it's interesting to see how a study with lots of limitations and reservations by the researchers now is misquoted, re-quoted, and popping up all over internet with 'vegetarians' in the title.

What's next? If they find some old study confirming that too high intake of carotene (found in carrots, carrot juice etc - a 'vegan product') may cause carotene poisoning, will we see headers saying 'Vegan food is poisonous"?

Re: Memory: Tempeh and tofu, for better or worse

Korn, can you see if the researchers controlled for any confounding variables, e.g. a possible effect of poverty on memory? There is some evidence that poor nutrition esp. in childhood contributes to the development of dementia in later life and I wonder if eating a lot of tofu could be linked to poverty in SE Asia.

They should also have controlled for the amount of fruit and veg eaten - if people who ate more tofu also tended to eat less fruit and veg for some reason, then the effect of eating fruit and veg should have been removed from the data before they tested for a correlation between tofu-eating and memory loss.

Re: Memory: Tempeh and tofu, for better or worse

Poverty wasn't listed as a separate parameter, but I was thinking along the same lines... I guess tofu is considered 'poor man's food' in many Asian areas, and Tahu Sumedang (deep fried tofu) is definitely sold on the street (see this link) in Sumedang, on of the three locations used for the study. Deep fried street food is sometimes kept heated for hours before it's eaten. The report doesn't say anything about how the eaten tofu was prepared, but since Sumedang is famous for it's Tahu Sumedang, we can always guess what they were eating...

Two of the three locations were in rural areas, and wherever I've been in Asia, the rural areas were always the poorest.

The local tofu speciality in Sumedang is made of soyabeans that both have been cooked and then deep fried, and if eaten by people which in many cases don't eat fruit/vegetables - some of them close to 100 years old, I'm not surprised that they have a weak memory - or that overcooked soy beans can contribute to the problem.

Most people in the study were farmers (36%) or had no work (31%), neither of which are known for having a lot of money to spend on healthy, varied fresh produce (and as I mentioned earlier - the people in the rural areas (almost all the farmers) ate less vegetables/fruit than those in Jakarta.

It's quite likely that most of the people in the study were low in a number of nutrients, and that a study among people who also eat fresh fruit, vegetables etc. wouldn't have the problems these people had from eating tofu - not only because the very brain-unfriendly formaldehyde isn't used as a preservative here, but because they would have a healthy level of antioxidants and folate from other food that would eliminate some of the effect of using tofu. Most likely, they wouldn't eat both tofu and tempeh at least once a day either - which most of the participants in this study did.

Only 39% of the participants said they were consuming fruit/juice, 31% used orange/red vegetables, and 49% used green vegetables (we're not talking about daily here - it looks like they didn't use these plants at all). Tahu Sumedang was served with green chili on the only picture I've seen of this tofu dish....

Between 65 and 67% of the participants group ate both tempeh and tofu daily or more... I see why they had to go this far to find someone with this high degree of (deep fried??) tofu consumption!

44% of the 298 people from Jakarta had high school or academy/university or higher - only a total of 7% of the whole group and higher education than high school. (In the rural rural locations the numbers were respectively 2% and 3% (high school only).

In one of the locations, 46% had no education at all (no elementary school either)... it looks like a study on a group (and a product) - that turns out to be very different from the typical veg*n (and his formaldehyde-free tofu) in the West.

Too much (double cooked) soy - either plain or "A La Formaldehyde" - still doesn't sound like a good idea!

In the Indonesian tempeh fermentation the content of riboflavin doubles, niacin increases seven-fold, and vitamin B12, which generally absent in vegetarian foods, is synthesized.

[...]

Although this would appear to be very advanced technology, the Indonesians for centuries have overgrown soaked, partially cooked soybean cotyledons with the mold Rhizopus oligosporus (as mentioned above), which knits the soybean cotyledons into a firm cake that can be sliced and deep-fat fried or used in chunks as a substitute for meat in soups. The protein content rivals that of meat and the cost is very low, within the means of the average Indonesian. Also, the microorganisms involved enrich the food with vitamin B12, increase niacin by a factor of seven, and double the riboflavin content.

Re: Memory: Tempeh and tofu, for better or worse

Thanks, Korn. I agree you can have too much of any one food, even tofu (and definitely formaldehyde ) but in the case of this particular study - well, as the abstract says "Future studies should validate these findings and investigate potential mechanisms."

Re: Memory: Tempeh and tofu, for better or worse

Sure. the somewhat ironic thing is that while this article now is all over the place in the Western world, the Indonesian participants (for whom the info about tofu overload and possible formaldehyde side effects) may not even see discussions like this. They got a bottle of vitamin pills from participating in the study - but do they know that Indonesian tofu commonly contains a chemical that is banned in Europe?

This info could be very relevant there, but where I live the research has been presented as 'a british study'. Indonesia wasn't mentioned with a single word.

From the ethical point of view I'm not sure if the researchers should feed their findings back to the participants or not. On the one hand it would be good to warn them not to eat too much tofu/formaldehyde but on the other hand if the damage is already done it wouldn't be good to cause anxiety. Sigh.